Edaravone

Edaravone is a free radical scavenger used in amyotrophic lateral sclerosis to slow functional decline in selected people with early disease. Its licence differs between regions, benefit is modest, and the intravenous schedule is demanding.

Mechanism. Scavenges free radicals and may reduce oxidative neuronal injury. The precise action in motor neurone disease is not fully defined.

Pharmacokinetics. Intravenous half-life is about 4.5 to 6 hours. It is metabolised by glucuronidation and sulphation, and excreted in urine as inactive metabolites. Oral suspension is absorbed and used at a higher dose.

Specialist use. Amyotrophic lateral sclerosis, in people who meet local criteria for early disease and preserved function.

• Intravenous edaravone: 60 mg once daily for 14 days, then 14 days without drug (first cycle). Following cycles: 60 mg daily for 10 days within each 14-day period, then 14 days without drug.

• Oral suspension (where available): 105 mg once daily, with the same cycle pattern of 14 days then 14 days off, and then 10 days of dosing within each 14-day period.

• Treatment continues while benefit is judged to outweigh burden, reviewed by the specialist.

Kidney, liver, weight and age.

• Kidney: no adjustment in the usual label; renal failure has been reported in some regions, so check creatinine.

• Liver: no adjustment.

• Older adults: no adjustment.

Contraindications. Hypersensitivity to edaravone or sodium bisulphite.

Serious adverse effects. Hypersensitivity reactions (hives, swelling, anaphylaxis), sulphite-related reactions including asthma attacks, and reduced respiratory function from the disease itself.

Common adverse effects. Bruising, gait disturbance, headache, dermatitis, eczema and glycosuria.

Interactions. No clinically important interactions are described.

Common prescribing errors. Wrong cycle timing. Mixing with other intravenous drugs in the same line. Not warning about sulphite allergy.

Special groups.

• Pregnancy: avoid unless clearly needed.

• Breastfeeding: avoid.

• Regional: very costly and seldom available, and it needs infusion access and cycle management.

Formulations. Intravenous bag 30 mg in 100 mL. Oral suspension 105 mg in 5 mL in some markets.

Preparation. Give two 30 mg bags (60 mg) as an infusion over 60 minutes, without further dilution. Do not mix with other drugs or solutions in the same bag.

Monitoring.

• Hypersensitivity during and after infusion, skin, and urinalysis for glucose.

• Creatinine at baseline and during treatment, and functional rating scale at each cycle.

Stopping. No taper is needed. Stop for severe hypersensitivity or lack of benefit.

Referral and escalation. Start only under a specialist motor neurone disease service.